She was just trying to help Inuyasha, feeling that his half-brother was being a worse jerk than the hanyou. Also at that time she could only see Sesshoumaru as just another power hungry youkai. Nothing much, simply going through the motion of helping her reluctant ally from getting killed due to his reckless and stubborn behavior. So when she managed to get the coveted blade out of its pedestal, she had pushed aside her confusion and swallowed her fear as she found their latest nemesis towering over her, a certain death looming over her dressed in fierce samurai getup.
He had asked her then, "What are you?"
Before she could answer, Inuyasha called his attention away from her. The taller of the brother, just another youkai to her, then questioned Inuyasha's pride as a youkai. He wondered, "Why protect them? Why miss them?" He brushed back his pale hair, "Why love them?"
"You may be adverse from killing a human due to your despicable human blood, but I Sesshoumaru, does not,"
That seemed to be the sign of her end as he turned those deadly claws onto her and poisonous mist poured out of his palm. That would have been the end but the jewel shard that was with her, the blades forged from the fang of the beast looming over them and the very air of Yomi as well as her untrained power seemed to have a rather extreme reaction to being exposed to each other.
Kagome screamed in both fear and shock while Sesshoumaru's golden gaze widened as Kagome's reiki reacted strongly against his attack while his own youki broke through his iron clad control. Inuyasha's call for her became lost along with Jaken's concerned squawk for Sesshoumaru as the immense energy still trapped within the bones of Inu no Taisho exploded all around them.
Myouga managed to force Inuyasha to move as his father's remains started to crumble all around them. He unconsciously grabbed Jaken on the way out and all three stared as the great general's remain that once loomed over his surrounding like a mountain crumbled into itself, dust bellowing all around him like a sandstorm made out of brittle bones.
Inuyasha waited out the storm before rushing in, screaming out for Kagome while coughing out the dust that managed to get into his throat, irritating it. The girl may be annoying, loud, and simply impossible to be with but he did dragged her into this mess with the jewel and now his bastard of a half-brother who seemed to falter between ignoring his existence and making it his mission to make his life hell. In fact, as Inuyasha found the twin blade forged by his sire's fangs, he was certain that unless it was because he couldn't avoid making contact with the hanyou Sesshoumaru would have forgotten completely about Inuyasha.
Which suite the hanyou just fine but not when a girl that he somewhat owe his freedom to managed to get herself involved with the heartless youkai. Kagome already have trouble with the small fries of the youkai society, she couldn't possibly handle a Daiyoukai like Sesshoumaru.
Inuyasha hate admitting it but Sesshoumaru could have laid all of Japan to waste with his strength alone had he been a blood lusting son of a bitch. And now a miko who can't shoot an arrow to save her life and a Daiyoukai who couldn't care less about another's life have gone missing.
Inuyasha managed to squeeze all three of them out of Yomi just as the portal that connect the Land of the Living and Yomi closed. Leaving a wailing imp behind, he confronted the flea that served as both his missing mentor and his useless guardian, "What happened back there?!"
Myouga's answer sent shiver down his spine, "I know not, Master Inuyasha,"